Low Leaf Dry Matter Content Research Articles

Climate factors determine the utilization strategy of forest plant resources at large scales.

Plant functional traits are a representation of plant resource utilization strategies. Plants with higher specific leaf area (SLA) and lower leaf dry matter content (LDMC) exhibit faster investment-return resource utilization strategies. However, the distribution patterns and driving factors of plant resource utilization strategies at the macroscale are rarely studied. We investigated the relative importance of climatic and soil factors in shaping plant resource utilization strategies at different life forms in forests using data collected from 926 plots across 163 forests in China. SLA and LDMC of plants at different life forms (i.e., trees, shrubs, and herbs) differ significantly. Resource utilization strategies show significant geographical differences, with vegetation in the western arid regions adopting a slower investment-return survival strategy and vegetation in warmer and wetter areas adopting a faster investment-return survival strategy. SLA decreases significantly with increased temperature and reduced rainfall, and vegetation growing in these conditions exhibits conservative resource utilization. Mean annual precipitation (MAP) is a key climatic factor that controls the resource utilization strategies of plants at the macroscale. Plants use resources more conservatively as soil pH increases. The influence of climate and soil factors is coupled to determine the resource utilization strategies of plants occupying different life forms at the macroscale, but the relative contribution of each varies across life forms. Our findings provide a theoretical framework for understanding the potential impact of increasing global temperatures on plant resource utilization.

Responses of chlorophyll fluorescence and non-structural carbohydrate accumulation of Castanopsis kawakamii seedlings to seed dispersal positions

When seeds fallen from the mother trees, their initial contact physical environment was litter or soil. The dispersal positions of seeds (seeds positioned on top of the litter, the soil surface and beneath the litter) determine the process of their natural regeneration. We simulated three different dispersal positions of Castanopsis kawakamii, including seeds positioned on top of the litter (2 and 4 cm litter was placed below the seed layer), soil surface (without litter), and seeds beneath the litter (2, 4, 6 and 8 cm litter covers in the upper layer of seeds). We examined the effects of seed dispersal position on the chlorophyll fluorescence characteristics, non-structural carbohydrate, specific leaf area, leaf dry matter content and nutrient content of seedlings. The results showed that leaf nitrogen content per area of seedlings had significantly positive correlation with soluble sugar content, non-structural carbohydrate content, and negative correlation with specific leaf area across different dispersal positions. Seedlings of the moderate litter cover (2 and 4 cm) adopted resource acquisitive strategies by increasing relative chlorophyll content, soluble sugar content, non-structural carbohydrate content, leaf dry matter content, leaf nitrogen content and phosphorus contents per area, and decreasing specific leaf area to achieve their demands for rapid growth. Seedlings grew on soil surface and beneath the deep litter (6 and 8 cm) adopted the resource conservative strategies with higher leaf nitrogen content per mass and specific leaf area, lower leaf dry matter content, and non-structural carbohydrate content to intercept more effective light resources to compensate for the shady environment brought by deep litter. This would further decrease the probability of seedling mortality due to 'carbon starvation'. Seedlings under litter layer stored starch in leaf, and reduced the energy consumption of photosynthetic tissues (low PSⅡ maximum photochemical efficiency) to maintain seedling growth. Comprehensive analysis of entropy method indicated that low amount of litter cover (2 cm) significantly promoted seedling growth of C. kawakamii. In the future, we could regulate the thickness of litter layer to promote the growth and regeneration of C. kawakamii seedlings in natural forest.

Liana litter decomposes faster than tree litter in a multispecies and multisite experiment

Abstract Lianas account for a small fraction of forest biomass, but their contribution to leaf or litter biomass and thus to food webs can be substantial. Globally liana exhibit fast life‐history traits. Thus, liana litter may decompose faster than tree litter, and could enhance the decomposition of tree litter (complementarity effect). The differences in decomposition may also vary with mesofauna access or across forest communities. The contribution of these factors to nutrient biogeochemical cycling is poorly understood. We examined the decomposition of litter of 20 liana and 20 tree species of three different tropical forest communities in southern China, over 1 year. (i) We incubated the litter in bags with coarse and fine mesh to distinguish mesofaunal and microfaunal effects. (ii) We used single‐species litter bags to compare decomposition rates of lianas and trees, to test which functional traits best explained decomposition, and whether those traits differed between lianas and trees, and among forest types. (iv) We used mixed‐species litter bags to test whether liana litter enhances decomposition in litter mixtures. (v) We evaluated how leaf litter nutrients decayed in relation to litter mass. Litter decayed faster in coarse‐mesh than fine‐mesh bags, but there was no interaction effect with forest type or growth form. Liana litter decayed faster than tree litter in single‐species bags with mesofauna access and in mixed bags (liana‐only mix, tree‐only mix) without mesofauna. Lianas had higher nitrogen content and specific leaf area and lower leaf dry matter content (LDMC) and toughness than trees. Decomposition rate was significantly negatively related to LDMC. Litter of evergreen broadleaved forest decomposed slower than that of other forest types. Liana litter did not enhance the decomposition of tree litter in mixtures. Liana litter released calcium slightly faster than trees. Synthesis: Leaf litter decomposes faster for lianas than trees, despite high variability of traits and decomposition rates within each growth form and overlap between growth forms, and we found no evidence for the complementarity hypothesis. Our study sheds light on the potential role of lianas within brown food webs and their importance on terrestrial biogeochemistry.

Climatic niche pre-adaptation facilitated island colonization followed by budding speciation in the Madeiran ivy (Hedera maderensis, Araliaceae).

The path followed by species in the colonization of remote oceanic islands ultimately depends on their phylogenetic constraints and ecological responses. In this study, we aim to evaluate the relative role of geographical and ecological forces in the origin and evolution of the Madeiran ivy (Hedera maderensis), a single-species endemic belonging to the western polyploid clade of Hedera. To determine the phylogenetic placement of H. maderensis within the western polyploid clade, we analyzed 40 populations (92 individuals) using genotyping-by-sequencing and including Hedera helix as outgroup. Climatic niche differences among the study species were evaluated using a database with 867 records representing the entire species ranges. To test species responses to climate, 13 vegetative and reproductive functional traits were examined for 70 populations (335 individuals). Phylogenomic results revealed a nested pattern with H. maderensis embedded within the south-western Iberian H. iberica. Gradual niche differentiation from the coldest and most continental populations of H. iberica to the warm and stable coastal population sister to H. maderensis parallels the geographical pattern observed in the phylogeny. Similarity in functional traits is observed for H. maderensis and H. iberica. The two species show leaves with higher specific leaf area (SLA), lower leaf dry matter content (LDMC) and thickness and fruits with lower pulp fraction than the other western polyploid species H. hibernica. Acquisition of a Macaronesian climatic niche and the associated functional syndrome in mainland European ivies (leaves with high SLA, and low LDMC and thickness, and fruits with less pulp content) was a key step in the colonization of Madeira by the H. iberica/H. maderensis lineage, which points to climatic pre-adaptation as key in the success of island colonization (dispersal and establishment). Once in Madeira, budding speciation was driven by geographical isolation, while ecological processes are regarded as secondary forces with a putative impact in the lack of further in situ diversification.

Natural selection favours drought escape and an acquisitive resource‐use strategy in semi‐arid Mediterranean shrubs

AbstractNatural selection is the major force driving adaptive evolution in natural populations, varying in strength, direction, and form through space and time, especially in highly variable environments such as Mediterranean ecosystems. Although a conservative resource‐use strategy has been hypothesized to be adaptive in Mediterranean taxa, patterns of selection at the intraspecific level, that is, the suite of traits determining individual fitness, are largely unknown.Using a phenotypic selection experiment in natural semi‐arid conditions, we measured direct and indirect selection acting through two different fitness components (survival and reproduction), to assess the adaptive value of 20 ecophysiological traits on individuals of two gypsum endemic species,Centaurea hyssopifoliaandHelianthemum squamatum, dwelling in environments with contrasting abiotic conditions (south‐ and north‐facing slopes) during two climatically contrasting years (dry and mesic). This allowed quantifying the magnitude and direction of natural selection at different spatiotemporal scales.Our results revealed that different abiotic conditions did not alter selection patterns, being the magnitude of selection more strongly affected by temporal environmental variation. Selection through reproduction indicated consistent selection for early phenology, low water use efficiency, high specific leaf area, low leaf dry matter content, and high leaf N across slopes and years in both species. In contrast, phenotypic trait variation was not linked to survival in either species. Furthermore, while individual reproductive output was higher or similar in environments with higher abiotic stress in both species and years, survival was similar across environmental conditions, and it was neither affected by plant size nor reproductive output.Contrary to our expectations, natural selection via reproductive fitness consistently favoured a drought‐escape, acquisitive resource‐use strategy in Mediterranean semi‐arid plants, rather than a conservative resource‐use strategy, even under conditions of higher abiotic stress (i.e. south slopes and dry year). Such acquisitive strategy could allow rapid development by maximizing resource assimilation and reproduction before the most limiting climatic conditions of mid‐late summer. Our results shed light on adaptive functional strategies of Mediterranean taxa at the intraspecific level, providing insight on future responses to environmental change, and highlight remarkable differences in selection acting through different fitness components.Read the freePlain Language Summaryfor this article on the Journal blog.

Functional composition of plant communities mediates biomass effects on ecosystem service recovery across an experimental dryland restoration network

Abstract Land degradation can result in a loss of critical ecosystem services that we often seek to restore through re‐establishment of desired plant communities. Trait‐based approaches have the potential to target specific ecosystem services based on associations between the functional composition of plant communities and ecosystem properties that serve as indicators of those services. The effect of functional composition on ecosystem recovery may depend on the amount of restored plant biomass, itself a supporting service frequently targeted in restoration efforts. Yet, interactions between functional composition and biomass are not formally integrated into trait‐based analytical frameworks. We tested the hypothesis that functional composition of plant communities both drives, and interacts with, biomass production to influence indicators of soil functioning and weed suppression across a network of degraded dryland restoration experiments. This networked approach allowed us to identify generalized effects of functional composition on ecosystem recovery across a range of dryland climate conditions. Climate had a substantial effect on ecosystem indicators, with weed cover and soil surface stability increasing in more arid climates, water infiltration increasing with precipitation, and aggregate structure increasing with less freezing. After accounting for climate effects across study sites, we found significant effects of community‐weighted mean (CWM) trait values on biomass, particularly a positive effect of leaf carbon‐to‐nitrogen ratio, and of CWM‐biomass interactions on other ecosystem indicators. Cover of exotic species was reduced in restored communities with a combination of low leaf dry matter content and high biomass, soil water infiltration increased with lower specific root length and high biomass, and soil aggregate stability increased with higher root dry matter content and high biomass, among other effects. Functional diversity had no significant effects on any ecosystem indicators. Synthesis: The influence of community functional composition on ecosystem properties increases with community biomass, particularly in disturbed or low productivity systems. This suggests that active management should not only focus on trait values that optimize individual ecosystem indicators but also how those functional strategies are complementary or counter to those that increase biomass. Read the free Plain Language Summary for this article on the Journal blog

Comparison of Leaf and Fine Root Traits Between Annuals and Perennials, Implicating the Mechanism of Species Changes in Desertified Grasslands.

Annual species show traits, such as shortleaf lifetimes, higher specific leaf area, and leaf nutrient concentrations, that provided a more rapid resource acquisition compared to perennials. However, the comparison of root traits between the annuals and perennials is extremely limited, as well as the trade-offs of leaf and fine root traits, and resource allocation between leaf and root, which may provide insight into the mechanism of species changes in arid and semi-arid areas. With lab analysis and field observation, 12 traits of leaf and fine root of 54 dominant species from Horqin Sandy Land, Northeastern China were measured. The organization of leaf and fine root traits, and coordination between leaf and fine root traits of annual and perennial plants were examined. Results showed that there were differences between annuals and perennials in several leaves and fine root traits important in resource acquisition and conservation. Annuals had higher leaf area (LA), specific LA (SLA), and specific root length (SRL) but lower leaf dry-matter content (LDMC), leaf tissue density (LTD), leaf carbon concentration (LC), and fine root dry-matter content (FRDMC) than perennials. Leaf nitrogen (LN) concentration and fine root nitrogen concentration (FRN) were negatively related to LTD and FRDMC in annuals, while FRN was positively related to FRTD and fine root carbon concentration (FRC), and LA was positively related to LN in perennials. These implied that annuals exhibited tough tissue and low palatability, but perennials tend to have smaller leaves to reduce metabolism when N is insufficient. Annuals showed significant positive correlations between FRC/FRDMC and LDMC/LTD/LC, suggesting a proportional allocation of photosynthate between leaf and fine root. In perennials, significant negative correlations were detected between LN, LC, and SRL, fine root tissue density (FRTD), as well as between LA and FRTD/FRC. These indicated that perennials tend to allocate more photosynthate to construct a deeper and rigid roots system to improve resource absorption capacity in resource-limited habitats. Our findings suggested that annuals and perennials differed considerably in terms of adaptation, resource acquisition, and allocation strategies, which might be partly responsible for species changes in desertified grasslands. More broadly, this work might be conducive to understand the mechanism of species changes and could also provide support to the management and restoration of desertified grassland in arid and semi-arid areas.

Relationships between above‐ground plant traits and carbon cycling in tundra plant communities

Abstract The trait composition and trait diversity of plant communities are globally applicable predictors of ecosystem functioning. Yet, it is unclear how plant traits influence carbon cycling. This is an important question in the tundra where vegetation shifts are occurring across the entire biome, and where soil organic carbon stocks are large and vulnerable to environmental change. To study how plant traits affect carbon cycling in the tundra, we built a model that explained carbon cycling (above‐ground and soil organic carbon stocks, and photosynthetic and respiratory fluxes) with abiotic conditions (air temperature and soil moisture), and the averages and within‐community variabilities of three above‐ground traits: plant height, leaf dry matter content (LDMC) and SLA. These functional parameters were represented by abundance‐weighted means and standard deviations of species traits. The data were collected from an observational study setting from northern Finland. The explanatory power of the models was relatively high, but a large part of variation in soil organic carbon stocks remained unexplained. Average plant height was the strongest predictor of all carbon cycling variables except soil carbon stocks. Communities of larger plants were associated with larger CO2 fluxes and above‐ground carbon stocks. Communities with fast leaf economics (i.e. high SLA and low LDMC) had higher photosynthesis, ecosystem respiration and soil organic carbon stocks. Within‐community variability in plant height, SLA and LDMC affected ecosystem functions differently. Variability in SLA and LDMC increased CO2 fluxes and soil organic carbon stocks, while variability in height increased the above‐ground carbon stock. The contributions of within‐community trait variability metrics to ecosystem functioning within the study area were about as important as those of average SLA and LDMC. Synthesis. Plant height, SLA and LDMC have clear effects on tundra carbon cycling. The importance of within‐community trait variability highlights a potentially important mechanism controlling the vast tundra carbon pools that should be better recognized. More research on root traits and decomposer communities is needed to understand the below‐ground mechanisms regulating carbon cycling in the tundra.

Intraspecific trait changes have large impacts on community functional composition but do not affect ecosystem function

Abstract Plant functional traits can provide a mechanistic understanding of community responses to global change and of community effects on ecosystem functions. Nitrogen enrichment typically shifts trait composition by promoting the dominance of acquisitive plants (high specific leaf area [SLA] and low leaf dry matter content [LDMC]), translating into high biomass production. Changes in mean trait values can be due to shifts in species identity, relative abundances and/or intraspecific trait values. However, we do not know the relative importance of these shifts in determining trait responses to environmental changes, or trait effects on ecosystem functioning, such as biomass production. We quantified the relative importance of species composition, abundance and intraspecific shifts in driving variation in SLA and LDMC, and how these shifts affected above‐ and below‐ground biomass. We measured traits in a grassland experiment manipulating nitrogen fertilisation, plant species richness, foliar fungal pathogen removal and sown functional composition (slow vs. fast species). We fitted structural equation models to test the importance of abundance and intraspecific shifts in determining (a) responses of functional composition to treatments and (b) effects on above‐ and below‐ground biomass. We found that species intraspecific shifts were as important as abundance shifts in determining the overall change in functional composition (community weighted mean trait values), and even had large effects compared to substantial initial variation in sown trait composition. Intraspecific trait shifts resulted in convergence towards intermediate SLA in diverse communities; although convergence was reduced by nitrogen addition and enhanced by pathogen removal. In contrast, large intraspecific shifts in LDMC were not influenced by the treatments. However, despite large responses, intraspecific trait shifts had no effect on above‐ or below‐ground biomass. Only interspecific trait variation affected functioning: below‐ground biomass was reduced by SLA and increased by LDMC, while above‐ground biomass was increased by SLA. Synthesis. Our results add to a growing body of literature showing large intraspecific trait variation and emphasise the importance of using field collected data to determine community functional composition. However, they also show that intraspecific variation does not necessarily affect ecosystem functioning and therefore response–effect trait relationships may differ between versus within species.

Linking soil nutrients and traits to seedling growth: A test of the plant economics spectrum

Investigating the link among plant growth rates, traits and local environmental heterogeneity is necessary for understanding forest dynamics and community assembly. Although recent results showed that aboveground traits are key for determining organism’s performance and main resource-use strategies, it is clear that organism performance is influenced by both above- and below-ground traits. However, we have limited understanding about how belowground strategies change in response to soil fertility and determine plant performance. We hypothesize that belowground traits have significant effects on plant performance and that shifts in soil nutrient variability are associated to shifts belowground traits. We tested these hypotheses by surveying plant communities including 3969 seedlings represented by 49 common species over a 10-year period, measured soil nutrients, including total nitrogen (TN), phosphorus (TP) and potassium (TK), and leaf and root traits to examine the links among soil nutrients, traits and growth. We first examined the coordination of leaf and root traits of community level, then used traits to predict individual and species mean height growth rate (RGRh). Finally, we tested for shifts in traits in response to gradients of soil nutrients. We found that community-level traits tended to be multidimensional. Species with acquisitive leaf traits, e.g., high leaf area ratio (LAR), phosphorus content (LP), specific leaf area (SLA) and low leaf dry matter content (LDMC), exhibited high growth rates. However, root traits were weak predictors of RGRh, all root traits were not significantly correlated to RGRh of species, only root tissue density (RTD), specific root area (SRA) and length (SRL) was significantly correlated with RGRh of individuals. Community-weighted mean traits only significantly changed along the gradients of limiting soil nutrients, especially for TK and TP. Species with high LN, SLA, root nitrogen content, SRA and SRL, and low tissue density associated with high TK and TP. Ultimately, multidimensional trait variations, and weak links between root traits and growth only partly support the plant economics spectrum (correlation among traits along one axis), but emphasizes that, beyond root traits, other resource uptake processes of roots should be linked to plant performances. Our findings provide further insights into the understanding of how ecological strategies regulate plant performances and shape potential responses of plant communities to environmental change.

Exploring Assembly Trajectories of Abandoned Grasslands in Response to 10 Years of Mowing in Sub-Mediterranean Context

Abandoned semi-natural grasslands are characterized by lower plant diversity as a consequence of tall grasses spreading. Mowing is a widely used restoration practice, but its effects to maintain the restored diversity over time is poorly investigated in sub-Mediterranean grasslands. Since 2010 in the central Apennines, we fenced a grassland, invaded by Brachypodium rupestre, which was mowed twice a year. Before the experiment started, we recorded species cover in 30 random sampling units (0.5 m × 0.5 m). The sampling was repeated every two years for a total of ten years. We used linear mixed-effect models to investigate the trajectory of functional diversity and community weighted mean for traits related to space occupation, resource exploitation, temporal niche exploitation, and Grime’s CSR strategies. The reduction of the weaker competitor exclusion exerted by B. rupestre affected the functional plant community. In the short term (4–6 years), this fostered space occupation strategies, decreasing convergence of clonal strategies and horizontal space occupation types. In the longer term (8–10 years), mowing filtered ruderal strategies, i.e., species with faster resource acquisition (lower leaf dry matter content, LDMC). LDMC and CSR strategies, initially convergent due to the dominance of B. rupestre, lowered convergence over time due to higher differentiation of strategies.

Functional diversity outperforms taxonomic diversity in revealing short-term trampling effects

Alpine grasslands harbor diverse groups of flora and fauna, provide important ecosystem functions, and yield essential ecosystem goods and services, especially for the development of nature-based tourism. However, they are experiencing increasing anthropogenic perturbations such as tourist trampling. Although negative effects of tourist trampling on alpine vegetation have been frequently reported, previous studies have focused mainly on changes in taxonomic diversity after trampling, and rarely provide a mechanistic elucidation of trampling effects from a trait-based perspective. The present study evaluates the impacts of simulated trampling on taxonomic and functional diversity of a typical alpine grassland community in Shangri-La, China using a standardized protocol. The results showed that although taxonomic diversity was not statistically significantly affected by trampling, some functional attributes responded rapidly to trampling disturbance. Specifically, functional divergence decreased with an increase in trampling intensity, and characteristics of community-weighted mean trait values changed towards shorter species with reduced leaf area and lower leaf dry matter content. Such strong shifts in functional attributes may further affect ecosystem goods and services provided by alpine grasslands. Our inclusion of functional diversity in the analysis thus adds an important caution to previous studies predominantly focusing on taxonomic diversity, and it is urgent to keep alpine grasslands well managed and ecologically coherent so that their valuable functions and services can be safeguarded.

Leaf Traits of Trees in Tropical Dry Evergreen Forests of Peninsular India

A plant functional trait study was conducted to know the existing relationship between important leaf traits namely, specific leaf area (SLA), leaf dry matter content (LDMC), and leaf life span (LL) in tropical dry evergreen forest (TDEFs) of Peninsular India. Widely accepted methodologies were employed to record functional traits. The relationships between SLA and LDMC, LDMC and LL, and SLA and LL were measured. Pearson’s coefficient of correlation showed a significant negative relationship between SLA and LDMC, and SLA and LL, whereas a significant positive relationship was prevailed between LDMC and LL. The mean trait values (SLA, LDMC, and LL) of evergreens varied significantly from deciduous species. SLA had a closer relationship with LDMC than LL. Similarly, LL had a closer relationship with SLA than LDMC. Species with evergreen leaf habits dominated forest sites under study. Evergreen species dominate the study area with a high evergreen-deciduous ratio of 5.34:1. The S strategy score of trees indicated a relatively higher biomass allocation to persistent tissues. TDEFs occur in low elevation, semiarid environment, but with the combination of oligotrophic habitat, high temperature and longer dry season these forests were flourishing as a unique evergreen ecosystem in the drier environment. The relationships found between leaf traits were in concurrence with earlier findings. Trees of TDEFs survive on the poor-nutrient habitat with a low SLA, high LDMC, and LL. This study adds baseline data on key leaf traits to plant functional trait database of India.

Zoochory on and off: A field experiment for trait‐based analysis of establishment success of grassland species

AbstractAimsWe tested the establishment success of grassland species in the presence or absence of zoochory by livestock and identified the traits associated with successful establishment.LocationHortobágy National Park, Hungary.MethodsIn six restored species‐poor grasslands we established two species‐rich 4 m × 4 m source plots per site in 2013. One source plot was managed by extensive cattle grazing (“zoochory on”), the other one was fenced and protected from grazers (“zoochory off”). We monitored the vegetation development in the source plots (2014–2018), and the establishment success of sown species (2016–2018) in adjacent dispersal plots in four, 20‐m‐long strips per source plot in a total of 960 dispersal plots. We calculated community‐weighted means of thirteen plant traits related to regeneration and competitive ability. The effect of grazing, year, distance from source plots, grazing–year and grazing–distance interactions on population and trait dynamics in the source and dispersal plots were analysed with generalized linear mixed‐effect models.ResultsAlthough grazing reduced the cover and flowering success of sown species in the source plots, the number of successful establishment events was higher in dispersal plots next to grazed source plots. The sown species were the most abundant in plots adjacent to source plots, but occurred at all monitored distances. Zoochory favoured perennial plants with high specific leaf area (SLA), low leaf dry matter content (LDMC), short stature, light seeds, early flowering period, high clonal index and anemochory index.ConclusionsWe showed that species that can colonize the matrix with and without zoochory have contrasting trait syndromes. In grazing‐adapted ecosystems, fencing source populations of target species does not always seem to be a good option. It was a good tool for increasing the cover and flowering success of the sown species in the short run, but it significantly decreased their chance to colonize the surrounding area in the long run.

Functional diversity and redundancy of subalpine meadows subjected to anthropogenic disturbances

Abstract Aims The aims of this study were to assess how functional diversity (FD) and functional redundancy respond to subalpine meadow ecosystem degradation under anthropogenic disturbance and how species contribute to functional redundancy along the disturbance gradient. Methods The study was carried out in the subalpine meadow in Mount Jade Dragon, which is located at the southeastern edge of the Tibetan Plateau. Four disturbance intensities [no disturbance (ND), weak disturbance (WD), moderate disturbance (MD) and severe disturbance (SD)] were identified. Species richness, soil properties and five key plant functional traits were assessed along the disturbance gradient. Simpson’s diversity index, FD based on the Rao algorithm, functional redundancy, community-weighted mean of each functional trait and species-level functional redundancy were determined. Important Findings Unimodal change pattern of FD and functional redundancy along the disturbance gradient were found in the present study, with their maximum in MD and WD, respectively. Species diversity showed a decreasing trend with increasing disturbance intensity. As disturbance intensified, species with traits related to conservative growth strategies, such as low specific leaf area (SLA) and high leaf dry matter content (LDMC), decreased, whereas species with resource acquisitive strategies, such as small plant, high SLA and low LDMC, increased in the community. At the species level, species showed species-specific roles in functional redundancy. Notably, some species were important in the community in terms of their unique function. For instance, Ligularia dictyoneura in ND and Potentilla delavayi in MD and SD.

Assessing the relationship between trait-based and horticultural classifications of plant responses to drought

Water availability can be a major abiotic constraint for plant success in urban areas. To ensure resilient green spaces, understanding which species are able to cope with low water availability is paramount for plant selection. However, in the horticultural industry, descriptions of species’ responses to low water availability are oftentimes poorly defined, inconsistent across sources, and informed from the natural habitat of species, personal experience, or both. Therefore, a method to objectively assess tolerances of species to low water availability is needed. Using a multivariate approach, we characterised the drought strategies of 113 horticultural plant species spanning five different growth forms (graminoids, herbs, climbers, shrubs and trees) by using five leaf-level traits (leaf mass per area (LMA), leaf thickness, unit leaf area, leaf dry matter content (LDMC) and leaf water potential at turgor loss point (TLP)). Based on this approach, we found that species clustered into three distinct groups, which correspond to fundamental drought strategies based on previous ecological literature (i.e., ‘dehydration avoiders’ (species with high LMA and LDMC, thick leaves and low (more negative) TLP), ‘dehydration tolerators’ (species with low LMA and LDMC and high (less negative) TLP) and an ‘intermediate’ mixture of the two strategies). We found that the majority of species that were considered as ‘drought tolerant’ by the horticultural industry were classified as either ‘dehydration tolerators’ (31.9 %) or ‘dehydration avoiders’ (42.5 %) using our trait-based approach. We did not find any strong connections between the climate of origin of our species and our trait-based classifications. Distinguishing between dehydration avoidance and dehydration tolerance may help to enhance horticultural guidelines by better informing which species are suitable for particular biophysical and landscape contexts. This trait-based approach allows for evidence-based evaluation of drought strategies of new and emerging species and cultivars that may be suitable for urban landscapes.

Plant CSR types in the north: comparing the morphological and morpho-physiological approaches.

The online version contains supplementary material available at 10.1007/s12298-021-00973-9.

Manipulating plant community composition to steer efficient N‐cycling in intensively managed grasslands

Abstract Minimizing nitrogen (N) losses and increasing plant N uptake in agroecosystems is a major global challenge. Ecological concepts from (semi)natural grasslands suggest that manipulating plant community composition using plant species with different traits may represent a promising opportunity to face this challenge. Here, we translate these trait‐based concepts to agricultural systems in a field experiment, aiming to reveal the main determinants of how plant community composition regulates N‐cycling in intensively managed grasslands. We focused on key N pools (plant N from soil and from biological N‐fixation, soil mineral N and N2O emissions) as well as on biological drivers of N‐cycling in soil (abundance of N‐cycling microbial communities, earthworm populations and arbuscular mycorrhizal fungi), using three common grass and one legume species in monoculture, two‐ and four‐species mixtures. We hypothesized that: (a) plant species mixtures increase plant N uptake, reduce soil mineral N concentrations and N2O emissions and promote the abundance of biological N‐cyclers; (b) legume presence stimulates N pools, fluxes and biological N‐cycling activity, (c) but in combination with a grass with acquisitive traits, more N is retained in the plant community, while N2O emissions are reduced. We found that mixtures increased plant N and lowered the soil mineral N pool compared to monocultures. However, plant species identity played an overarching role: Legume presence increased N2O emissions, plant N pools, soil mineral N and the abundance of N‐cycling microbes and earthworms. Combining the legume with a grass with low leaf dry matter content and high root length density (and with high root biomass) reduced the higher soil mineral N and N2O emissions induced by the legume, while harnessing positive effects on plant N pools and biological N‐fixation. Synthesis and applications. Our results show the potential of plant community composition to steer N‐cycling in fertilized agroecosystems, paving the way for a more biologically based agriculture. Legumes will play a crucial role, but selecting an optimum companion species is key for the sustainability of the agroecosystem.

Not so stressful after all: Epiphytic individuals of accidental epiphytes experience more favourable abiotic conditions than terrestrial conspecifics

Vascular epiphytes are mainly associated with tropical and subtropical forest ecosystems. However, the frequent occurrence of accidental epiphytes in temperate forests proves that epiphytic growth of vascular plants is possible in tree crowns at these latitudes. Comparing the abiotic conditions of epiphytic and terrestrial microhabitats in conjunction with intraspecific differences in functional traits of the inhabiting plants, we identified limitations to vascular epiphytism in the study area in a Central European low mountain range. We determined light availability, winter temperatures, soil moisture, nutrient concentrations, and pH of arboreal soil in crotches of broad-leaved trees and in the immediate vicinity of each tree on the ground. Similarly, we quantified total plant water content, relative foliar chlorophyll content, specific leaf area (SLA), leaf dry matter content (LDMC), root-mass fraction, and aboveground nutrient concentrations of 110 pairs of epiphytic and terrestrial conspecifics. Water and nutrient availability were generally high in crotches filled with arboreal soil, suggesting better growth conditions than on the ground. A trophic advantage of epiphytic individuals over terrestrial conspecifics can be deduced from higher plant nutrient concentrations, higher SLA, and lower LDMC. Advantageous growth conditions might even result in higher growth rates and higher fitness of epiphytic individuals. Our findings highlight that vascular epiphytism in the study area is not necessarily limited by abiotic conditions but at least partly by the availability of old and structurally diverse trees providing suitable microhabitats. Accordingly, management actions in these secondary forest ecosystems should incorporate the preservation of old and large deciduous trees in order to sustain arboreal microhabitats and the associated biota.

Estrategias de tres especies arbustivas del Monte frente al estrés hídrico y su relevancia para la restauración

Knowing the different strategies of shrub species in arid zones allows selecting them to restore a specific site. According to Grime’s strategy scheme, plants of arid zones diverge into two main types: stress-tolerant, on the one hand, and ruderal, on the other. The objective of this study was to evaluate the adaptations to water stress of three shrub species (Atriplex lampa, Larrea cuneifolia and Senecio subulatus) widely distributed along the Monte region, as to be able to select them properly in future restoration projects. Three levels of water stress (watered when soil water content decreased by 50, 70 and 85%, control, moderate and severe water stress, respectively) were applied to 60 seedlings per species in a glasshouse study; pressure-volume curves were obtained and then, dry weight, tissue water relations parameters and ecophysiological indices associated with drought tolerance were measured. The strategies according to Grime were obtained using the StrateFy tool. Under severe water stress, the three species accumulated less dry matter and decreased their leaf area, and the growth of S. subulatus was the most affected. A. lampa and L. cuneifolia showed low leaf dry matter content, and A. lampa had the lowest specific leaf area. Through these foliar characters, the three species were classified as stress-tolerant according to Grime. Besides, A. lampa and L. cuneifolia perform osmotic adjustment under water stress conditions, while S. subulatus maintains high water potentials and does not modify its hydric parameters under these conditions. Therefore, S. subulatus has few mechanisms to cope with water stress and could be used to restore microsites where water accumulates, while A. lampa and L. cuneifolia, due to their stress-tolerant characteristics, are recommended for wide use to restore degraded areas of the Monte region.